<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
    </head>
    <body>
        <h1>首页</h1>
        用户名：<span id="username"></span>
        <div id="box"></div>
    </body>
    <script>
        window.onload = function () {
            let username = localStorage.getItem('user')
            if (username) {
                document.querySelector('#username').innerHTML = username
            } else {
                alert('请先登录')
                location.href = 'index.html'
            }
        }
    </script>
</html>
